Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/005—Processes for mixing polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/12—Polysiloxanes containing silicon bound to hydrogen
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
  • C08G77/16—Polysiloxanes containing silicon bound to oxygen-containing groups to hydroxyl groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G77/00—Macromolecular compounds obtained by reactions forming a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon in the main chain of the macromolecule
  • C08G77/04—Polysiloxanes
  • C08G77/14—Polysiloxanes containing silicon bound to oxygen-containing groups
  • C08G77/18—Polysiloxanes containing silicon bound to oxygen-containing groups to alkoxy or aryloxy groups

Definitions

• the present invention relates to aqueous silicone-organic compositions.
• the invention relates to compositions prepared by mixing a water-soluble organic polymer solution with an aqueous emulsion of a silicone polymer which employs emulsifying agents based on specific non-ionic surfactants and a water-soluble organic polymer.
• silicone-organic coatings have long been appreciated in the art for their ability to withstand high temperatures and the ravages of harsh climatic environments.
• the silicone resins have found particular utility in electrical insulation applications, as additives for organic paints and coatings and, when combined with minor portions of a silicone fluid, as excellent release coatings in bakeware applications. Silicone resins have also been successfully added to, e.g., alkyd compositions to improve weather resistance of the latter.
• the aqueous silicone-organic hybrids of the present invention do not suffer from the above noted drawbacks.
• the aqueous silicone emulsion component employed in their preparation requires a relatively low quantity of emulsifying agents and the excellent thermal resistance of the resulting silicone-organic coatings is therefore not significantly compromised relative to an all-silicone system which is applied from organic solvent solution.
• hybrid refers to the dual nature of the water-based compositions of the present invention, wherein a silicone emulsion is combined with an aqueous solution of a water-soluble polymer.
• the aqueous silicone-organic hybrids of the present invention are prepared by mixing (A) an aqueous silicone emulsion with (B) a water solution of a water-soluble polymer.
• the aqueous silicone emulsion results when an oil phase, containing (I) a silicone resin or liquid; optionally, (II) a water-immiscible solvent system; and (III) a specific non-ionic surfactant, is thoroughly dispersed in a water phase containing (IV) poly(vinyl alcohol); and (V) water.
• oil phase it is meant herein a liquid or semi-solid material, such as a freely flowing oligomer or a slowly flowing gum, resin or solution thereof.
• Component (I) of the present invention is a silicone polymer selected from the group consisting of a silicone resin, a silicone liquid or a combination of these.
• a general class of silicone polymers suitable for use as component (I) of the present invention is a compound having at least two silicon atoms per molecule and the average formula R x SiO (4-x)/2 (i) (i) wherein R denotes a hydrocarbon or substituted hydrocarbon radical and the value of x can be in the range of about 1 to 3.
• R denotes a hydrocarbon or substituted hydrocarbon radical and the value of x can be in the range of about 1 to 3.
• These compounds can further comprise various amounts of silicon-bonded radicals, such as hydroxy, alkoxy and hydrogen.
• the organic substituent R of formula (i) may be selected from radicals containing one or more atoms selected from the group consisting of nitrogen, oxygen, sulfur, fluorine, chlorine, amido, amino, carboxy, epoxy or mercapto radicals, inter alia.
• suitable hydrocarbon radicals include alkyl radicals, such as methyl, ethyl, isopropyl, isobutyl, hexyl, octyl, dodecyl and octadecyl; alkenyl radicals, such as vinyl, allyl and cyclohexenyl; and aryl radicals, such as phenyl, benzyl and tolyl.
• Suitable substituted hydrocarbon radicals include chloropropyl, 3,3,3-trifluoropropyl, mercaptopropyl, amine-substituted radicals such as beta-aminoethylamine-substituted alkyl radicals and their partially or fully acylated derivatives, epoxy-substituted alkyl radicals such as glycidoxypropyl and carboxyalkyl radicals such as S-carboxymethylmercaptoethyl and its ester derivatives.
• One type of silicone resin according to the invention may be represented by the above formula (i) wherein x has a value from 1.0 to 1.9, preferably from 1.3 to 1.7, and contains significant amounts, such as up to 25% by weight, of silicon-bonded hydroxy and/or alkoxy having 1 to 3 carbon atoms, typically methoxy radicals. Said silicon-bonded hydroxy and/or alkoxy radicals are reactive so that the silicone resin can be crosslinked and/or reacted with other components, such as silicone fluids and/or liquid organic resins bearing reactive sites.
• Preferred silicone resins comprise copolymers of at least two units selected from the group consisting of MeSiO 3/2 units, Me2SiO 2/2 units, PhMeSiO 2/2 units, PhSiO 3/2 units, Ph2SiO 2/2 units and PrSiO 3/2 units.
• Me denotes a methyl radical
• Ph denotes a phenyl radical
• Pr denotes a propyl radical.
• the preferred resin copolymers have from about 0.5 to about 6 weight percent residual hydroxyl radicals attached to the silicon atoms thereof, a total molar organic group to silicon ratio of 1 to 1.7 and a total molar phenyl group to silicon ratio of 0.35 to 0.85. It is further preferred that such a resin is combined with up to about 5 percent by weight of a liquid silicone, described infra, to form the silicone polymer (I).
• Silicone resins are well known in the art, many being commercially available, and need no detailed delineation herein. Briefly, silicone resins are typically prepared by hydrolyzing one or more hydrolyzable organosilanes and, optionally, "bodying” (i.e., condensing) the hydrolyzate to effect the formation of siloxane linkages.
• the organic groups of the organosilanes can be any of the hydrocarbon or substituted hydrocarbon radicals delineated above; however, they are typically methyl radicals and mixtures thereof with phenyl radicals.
• the methyl and phenyl radicals can be introduced into the silicone resin as various mixtures of monomethylsiloxy units, dimethylsiloxy units and monophenylsiloxy units.
• the hydrolyzable radicals of the organosilanes are typically chlorine or methoxy radicals, although other hydrolyzable radicals are sometimes used.
• silicone resin contemplated herein is a resinous copolymeric siloxane which consists essentially of R'3SiO 1/2 (ii) siloxane units and SiO 4/2 siloxane units in a molar ratio which provides from 0.6 to 0.9 R'3SiO 1/2 units for every SiO 4/2 unit.
• Each R' in formula (ii) independently denotes a monovalent hydrocarbon radical; such as an alkyl radical, such as methyl, ethyl, isopropyl, butyl and hexyl; an alkenyl radical, such as vinyl and allyl; an aryl radical, such as phenyl, tolyl and xylyl; an arylalkyl radical, such as beta-phenylethyl and beta-phenylpropyl; and a cycloaliphatic radical, such as cyclopentyl and cyclohexyl.
• a monovalent hydrocarbon radical such as an alkyl radical, such as methyl, ethyl, isopropyl, butyl and hexyl
• an alkenyl radical such as vinyl and allyl
• an aryl radical such as phenyl, tolyl and xylyl
• an arylalkyl radical such as beta-phenylethyl and beta
• all R' radicals in formula (ii) are lower alkyl radicals, although a minor portion of them can be replaced with other monovalent hydrocarbon radicals such as the vinyl radical and/or the phenyl radical to provide additional properties for the resinous copolymer such as the reactivity attendant therewith.
• the resinous copolymeric siloxane consists essentially of (CH3)3SiO 1/2 siloxane units and SiO 4/2 siloxane units in the molar ratio of about 0.75:1.
• These resins are also well known in the art and may be prepared in an organic solvent by a method outlined by Daudt et al. in United States Patent No. 2,676,182, for example.
• Liquid silicone polymers which may be emulsified in water according to the present invention may be linear, branched or cyclic species, also represented by the general formula (i), wherein the value of x is about 1.9 to 3.
• this liquid component is a diorganopolysiloxane homopolymer or copolymer, such as polydimethylsiloxane, polyphenylmethylsiloxane, polytrifluoropropylmethylsiloxane or copolymers thereof, having a number average molecular weight of about 103 to 107.
• the terminal groups on the diorganopolysiloxane are not critical and may be illustrated by such groups as trimethylsiloxy, phenyldimethylsiloxy or hydroxydimethylsiloxy.
• a highly preferred liquid diorganopolysiloxane is hydroxydimethylsiloxy-terminated polydimethylsiloxane having an average molecular weight of 1,000 to 50,000.
• liquid silicone polymers described above are also well known in the art and many are available commercially. In brief, they may be prepared by the hydrolysis and subsequent condensation of the respective chlorosilanes or by the alkaline equilibration of cyclic diorganosiloxanes in the presence of endblocking species.
• a water-immiscible solvent system (II) is optionally included in the oil phase of the emulsions of the present invention.
• this solvent system consists of about 99.5 to about 95 percent by weight of a first organic solvent and about 0.5 to about 5 weight percent of a coalescing solvent.
• the solvent system is required as an aid to film formation when component (I) is predominantly resinous, but is not necessarily used when (I) is a liquid polymer.
• the main restrictions on component (II) are that it not be miscible with water (i.e., it forms two phases when mixed therewith), that it be a relatively good solvent for the silicone component used and that it be essentially inert with respect to the other components and therefore not interfere with the respective intended purposes thereof.
• the coalescing solvent must have a boiling point considerably greater than that of water, as is well established in the art.
• the first solvent include toluene, xylene, mineral spirits and VM&P Naphtha.
• the coalescing solvent include alkyl acetates, 2,2,4-trimethylpentanediol 1,3-monoisobutyrate, ethylene glycol monobutyl ether acetate, ethylene glycol monomethyl ether acetate and high-boiling aromatic solvents, among others.
• Component (III) is a non-ionic surfactant selected from the specific compounds described infra.
• the non-ionic surfactant may be a sorbitan monoester of a carboxylic acid having 8 - 12 carbon atoms.
• these materials include sorbitan monocaprylate, sorbitan monopelargonate, sorbitan monocaprate, sorbitan monolaurate and sorbitan monomyristate.
• this surfactant is sorbitan monolaurate, marketed under the name ARLACELTM by ICI Americas, Inc., Wilmington, DE.
• a second suitable non-ionic surfactant is a polyethylene alkyl ether having the average formula CH3(CH2) m (OCH2CH2) n OH in which m is 7 to 15 and n is 2 to 50.
• a third non-ionic surfactant of the invention is a alkylphenoxy polyethoxy ethanol having the average formula C r H 2r+1 (C6H4)O(CH2CH2O) s CH2CH2OH in which r is 4 to 8 and s is 7 to 40.
• These compounds are commercially available, e.g., from Rohm and Haas (Philadelphia, PA) under the trade name TRITONTM.
• the poly(vinyl alcohol) (IV) of the invention is well known in the art.
• this component is partially hydrolyzed, has a number average molecular weight between about 30,000 and 50,000 and is employed herein as a water solution, as described infra.
• the water-soluble polymer (VI) may be any nonionic organic polymer or copolymer which is miscible with water. These materials are well known in the art and have, for example, frequently served as the organic binder component in conventional waterborne paints and coatings. Specific examples of the water-soluble polymers include acrylics, alkyds, urea formaldehydes, epoxy esters, methylated melamines, phenolics, polyamides and polyesters. An extensive enumeration of specific commercial examples of the above systems may be found in the tables provided in Chapter 5 of Waterborne Coatings (C. R. Martens, Van Nostrand Reinhold Co., New York, 1981). Additionally, this polymer may comprise carboxy-functional polymers, such as alkyds and acrylics, which have been rendered water-miscible by neutralization with ammonia or an amine, as commonly employed in the art.
• the water-soluble polymer is selected from the group consisting of acrylic, polyester or alkyd homopolymer or copolymer which may contain reactive groups capable of providing a means for curing the organic polymer. Most preferably, this component is an acrylic polymer or copolymer.
• Component (VII) is a water-miscible coalescing solvent which, in this case, aids in film formation of the water-soluble polymer (VI). It has essentially the same limitations as component (II) with the exception that it is compatible with water.
• solvents include ethylene glycols; alcohols, such as butanol, hexanol and 2-ethylhexanol; glycol ethers, such as ethylene glycol monobutyl ether and ethylene glycol monomethyl ether; and ketones, inter alia.
• compositions of this invention typically comprise additional components to aid in the curing of the silicon polymer (I) and/or the water-soluble organic polymer (VI).
• suitable cure-aiding components include well known curing catalysts for silicone polymers, such as compounds of lead, tin, titanium, cobalt, iron, magnesium and zinc.
• compositions of this invention can further incorporate components such as pigments, fillers, adhesion promoters, antifoams, flow agents, thickeners, biostats, freeze-thaw stabilizers and odorants which are commonly used in silicone and organic water-based emulsions and, particularly, in emulsions for coating applications.
• pigments fillers, adhesion promoters, antifoams, flow agents, thickeners, biostats, freeze-thaw stabilizers and odorants which are commonly used in silicone and organic water-based emulsions and, particularly, in emulsions for coating applications.
• Incorporation of pigments in the various coating formulations is preferred but it has been observed that their addition directly to the silicone emulsion (A) destabilizes the latter and is therefore not recommended.
• an aqueous silicone emulsion (A) is first prepared according to the methods described in copending application Serial No. 07/606,235, cited supra.
• This silicone emulsion is obtained when an oil phase is prepared by thoroughly mixing 100 parts by weight of silicone polymer (I) with up to about 50 parts by weight of coalescing solvent (II) and the requisite amount of the non-ionic surfactant (III).
• silicone polymer (I) silicone polymer
• coalescing solvent (II) coalescing solvent
• III non-ionic surfactant
• a water phase is prepared by dissolving the water-soluble polymer (IV) in at least 80 parts by weight of water (V).
• water (V) water
• the total amount of said non-ionic surfactant (III) and said poly(vinyl alcohol) (IV) that is used is the minimum required to produce a stable (i.e., non-separating), uniform emulsion, with the proviso that the weight ratio of said poly(vinyl alcohol) (IV) to said non-ionic surfactant (III) is between about 0.01 and 10, preferably 0.05 to 4.
• the amount of (III) and (IV) varies with the specific resin or liquid silicone polymer being dispersed and its value may be readily determined by the skilled artisan through routine experimentation. In general, a minimum of about 1.5 parts by weight of the sum of components (III) and (IV) are employed for each 100 parts by weight the silicone polymer (I). When more than about 7.5 parts by weight of (III) and (IV) are so employed, however, no additional emulsion stability is imparted and the excess of these components has been found to detract from the excellent high temperature properties of the silicone polymers.
• the silicone emulsions are prepared by mixing the above described water phase with the oil phase to form a silicone oil-in-water emulsion. While it is possible to add the water phase to the oil phase while vigorously stirring the mixture, it is highly preferred to slowly add the oil phase to the water phase while mixing is continued until the mixture becomes an oil-in-water emulsion and the desired size of oil particle is obtained.
• Any mixing means can be used in the above described process provided that it is capable of intimately mixing the components of the emulsion to be prepared.
• suitable mixing means include, but are not limited to, impeller mixers, mixers having sigma blades or Cowles blades, colloid mills, Sonolator, homogenizer, Micro fluidizer and planetary mixers.
• the oil-in-water silicone emulsions prepared according to the above described methods may be diluted with additional water, the amount of which is not narrowly limited provided a stable emulsion is maintained. For example, from about 10 to 1,900 parts by weight of water for every 100 parts by weight of the silicone polymer can be used. However, emulsions which are rich in water require longer periods of mixing than emulsions which are rich in water-insoluble oil. Consequently the amount of water to be used in this invention to form the emulsion is preferably limited to less than 350 parts by weight and, most preferably, less than 100 parts by weight per 100 parts by weight of the silicone polymer.
• the water that is used in this invention is preferably deionized or distilled.
• the above described silicone emulsion (A) is then thoroughly mixed with an aqueous organic polymer solution (B) of the present invention.
• the latter is prepared by thoroughly mixing 100 parts by weight of the water-soluble organic polymer (VI), up to about 15 parts by weight of the coalescing solvent (VII) and at least 50 parts by weight of water using any of the above mentioned mixing means.
• pigments are incorporated in the compositions of the present invention, they are dispersed in the aqueous organic polymer solution (B). It is contemplated that the weight ratio of the silicone polymer (I) to the water-soluble organic polymer (VI) in the final silicone-organic hybrid composition is between about 15:1 and 1:1, preferably between 13:1 and 5:1.
• compositions prepared according to this invention are expected to have the same utility as other water-based silicone or silicone-organic, oil-in-water systems of the art, such as for coating applications including coil coatings, automotive coatings, industrial and marine maintenance coatings and antifouling coatings. They are particularly suitable for the preparation of high temperature resistant and corrosion resistant coatings and paints.
• silicone polymer (I) is a silicone resin combined with up to about 5 weight percent of a silicone fluid, such as polydimethylsiloxane
• the compositions of the present invention produce excellent coatings for bakeware applications.
• AIRVOLTM 205 is a partially hydrolyzed poly(vinyl alcohol) having a molecular weight in the range of about 30,000 to 50,000 and marketed by Air Products (Allentown, PA).
• ARLACELTM 20 is sorbitan monolaurate having an HLB (hydrophilic/hydrophobic balance) of 8.6 and marketed by ICI Americas, Inc. (Wilmington, DE).
• BK 4799 is black iron oxide powder from Pfizer Inc. (New York, NY).
• CYMELTM 1156 is a butylated melamine resin marketed by American Cyanamide Co. (Wayne, NJ).
• DOWANOLTM PM is propylene glycol methyl ether obtained from the Dow Chemical Co. (Midland, MI).
• EXXATETM 900 is a solvent consisting essentially of nonyl acetate obtained from Exxon Chemicals (Houston, TX).
• FLUID 1 is a hydroxyl endblocked polydimethylsiloxane having the average formula HOMe2SiO(Me2SiO)540H wherein Me hereinafter denotes a methyl radical.
• GEL WHITETM is a clay rheology control agent marketed by EEC America (Gonzales, TX).
• JONCRYLTM 61 is an aqueous acrylic resin solution consisting essentially of 35% acrylic resin, 7.5% ammonium hydroxide, 1.5% ethylene glycol, 5.0% isopropyl alcohol and 51% water and having a pH of 8.3-8.6; it is marketed by Johnson Wax (Racine, WI).
• MEARLIN SUPER SPARKLETM is a mica-treated titanium dioxide pigment marketed by Mearl Pigment Co. (New York, NY).
• R-960 is a titanium dioxide pigment marketed by E. I. Du Pont (Wilmington, DE).
• RESIN 1 is a solid, hydroxyl functional organosiloxane resin copolymer consisting essentially of MeSiO 3/2 units, PhMeSiO 2/2 units, PhSiO 3/2 units and Ph2SiO 2/2 units, in a molar ratio of 45:5:40:10, in which Me hereinafter denotes a methyl radical and Ph hereinafter denotes a phenyl radical and having a hydroxyl content of about 5%.
• RESIN 2 is an 80% toluene solution of a hydroxyl functional organosiloxane resin copolymer consisting essentially of MeSiO 3/2 units, Me2SiO 2/2 units, PhSiO 3/2 units and Ph2SiO 2/2 units in a molar ratio of 25:20:35:20 and having a hydroxyl content of approximately 3%.
• RESIN 3 is an 50% (in 1:1 xylene:toluene) solution of a hydroxyl functional organosiloxane resin copolymer consisting essentially of MeSiO 3/2 units, Me2SiO 2/2 units, PhSiO 3/2 units and Ph2SiO 2/2 units in a molar ratio of 25:19:37:19 and having a hydroxyl content of approximately 0.5%.
• RESIN 4 is a blend consisting of 70% of said RESIN 2 and 30% of said RESIN 3.
• SC 150 is an aromatic solvent having a boiling point of about 362°F. obtained from Chem Central (Chicago, IL).
• An oil phase consisting of 28.6 parts of RESIN 1, 6.6 parts of SC 150 solvent, 1.3 parts of EXXATETM 900 solvent, 1.8 parts of ARLACELTM 20 and 1.8 parts of FLUID 1, was prepared by thoroughly mixing these ingredients. A total of 21 parts of this oil phase was added to 3 parts of a 2.5% water solution of AIRVOLTM 205 in a Myers mixer over a period of about 22 minutes. Agitation was provided by a Cowles blade operating at 835 rpm and an anchor blade operating at 83 rpm, this agitation being continued for an additional ten minutes.
• the emulsion so formed was mixed for an additional 20 minutes (Cowles blade at 2,577 rpm; anchor blade at 142 rpm), whereupon 4 parts of dilution water was added to form a stable oil-in-water emulsion.
• Paint "grinds” shown in Table 1 were prepared by mixing the ingredients on an Eiger mill at 2,000 rpm to obtain suspensions having a value of 8 on the Hegman gage. Each of these grinds was then mixed with 100 part portions of the silicone resin emulsion prepared in Example 1 to provide stable, water-based, silicone-organic coating compositions. Each composition was reduced to 45% non-volatile content with deionized water, sprayed onto aluminum panels, air dried for 20 minutes at room temperature and then cured at 600°F. for 5 minutes.
• a silicone emulsion was prepared according to the methods described in Example 1, wherein the oil phase consisted of 54.8 parts of RESIN 1, 12.5 parts of SC 150 solvent, 2.5 parts of EXXATETM 900, 3.4 parts of ARLACELTM 20 and 3.4 parts of FLUID 1.
• the water phase consisted of 11.4 parts of a 2.5% aqueous solution of AIRVOLTM 205. After dispersing the oil phase in the water phase, an additional 12.0 parts of water were added to form a silicone emulsion.
• the second grind composition shown in Table 3 was mixed with the above silicone emulsion in a ratio of 16.7 to 83.35 respectively, to form a coating composition which was applied to steel and aluminum substrates and cured thereon at 600°F./5 minutes.
• the cured films passed the above mentioned crosshatch adhesion (i.e., 100% adhesion), food release/stain resistance and steam resistance tests and were additionally subjected to the following tests.
• Water Soak Resistance Determined by soaking test panels in water for 24 hours. The coatings are then inspected for visible changes, as in the above described steam resistance test.
• Heat Resistance Evaluated by heating the coated panel to 550°F. for one hour, cooling to room temperature and inspecting the coating. Failure is indicated by a change in appearance, loss of adhesion or cracking. This procedure is repeated at 50°F. increments up to 700°F. Exposure for a period of two hours at the latter temperature without a visible effect indicates a passing condition.
• Example 7 The results obtained on the silicone-organic coating of Example 7 were at least as good as those observed for coatings based on a comparable all-silicone resin, applied from organic solvent solution. These results indicate that the modification of the silicone resin with an organic polymer, according to the methods of the present invention, does not detract from the former's excellent heat resistance properties.

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• 1990
  • 1990-10-31 US US07/608,048 patent/US5145898A/en not_active Expired - Fee Related
• 1991
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  • 1991-10-15 EP EP19910309461 patent/EP0484000A3/en not_active Withdrawn
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